In the context of the triple pressures in China’s economic development，urban digital economy has become a major party for stable growth. On the demand side，urban digital economy digs out the potential of urban domestic demand，drives industrial upgrading，and maximizes resource utilization. On the supply side，enterprises effectively use information and communication technology to improve the efficiency of industrial chains，supply chains and value chains，and enhance the supply capacity of urban products，technologies and services through smooth flow of urban data elements. In terms of expectations，China’s national development strategy for digital economy continues to improve. Industrial and local digital economy strategies have been implemented，providing policy and other support for the urban digital economy. The mature policy environment in megalopolises，complete digital foundation，rich data elements and advantageous digital industry foundation provide opportunities and advantages for the development of the digital economy in megalopolises. In order to develop the digital economy in megalopolises，we should optimize business environment，formulate the core industry chain of the urban digital economy，accelerate the digital transformation of SMEs，promote the utilization of urban data resources and explore the data-driven smart city.